Leica DM4000M microscopySuper sucker. Copper needles could help remove oil from the ocean. Researchers looking for a better way to clean up oil spills are taking a cue from the humble cactus. A new study shows that synthetic needles based on those of the desert plant can take up oil droplets from the ocean much as the cactus takes up water from the air.Cactus needles have a curious effect on water. When tiny water droplets in the air land on them, the needlesÂ’ conical shape distorts them, nudging them into a clamlike shape. Because water droplets like to be circular,...